SilverCity uses the lexer from Scintilla. Scintilla supports more languages than SilverCity implements. If you want to add a language to SilverCity supported by Scintilla, it's not very difficult. See SilverCityAddLanguage for some information how.

About Pygments

Starting with trac 0.11 pygments will be the new default highlighter. It's a highlighting library implemented in pure python, very fast, easy to extend and well documented. While it does not support as many languages as Enscript or Scintilla the overall output quality is much better.

To use pygments trac 0.11 you just have to install pygments 0.5.1 or higher. If you want to use it in trac 0.10 too you have to install the TracPygmentsPlugin from trac hacks. If you encounter any bugs, please file tickets regarding Pygments in the pygments trac.

It's very likely that the list below is outdated because the list of supported pygments lexers is growing weekly. Just have a look at the page of supported lexers on the pygments webpage.